There have been updates for N64 (both for Wii64 and Not64) and PS1 with a new fork, WiiSXR.
FCE Ultra RX is basically a continuation of GX, adding and improving things.
SNES9x RX is a bit different, as its focus is to have better performance, while SNES9x GX aims to be more accurate (at the cost of said performance). Both have their uses, of course.
I do not know if there's a VBA RX fork, but the GX version hasn't been updated in years. What we have though is mGBA, and is much, much better than VBA was (unless you care more about user interface than the actual emulation). Runs many games at full speed, and it can also be used to play GB and GBC games (although VBAGX works well for those too, and may have a few features that mGBA does not) There's an alternate version called Enhanced mGBA with extra options.
Genesis Plus GX has been updated constantly, but it has been a veeery long time since Eke Eke put a new, updated package for download. If you want newer versions you have to go to BitBucket and download the DOL file by yourself by looking at the latest edits.
In all honestly though, if you want to use your Wii for emulation what you really want to have independently of what other emulators you get, is RA-SS (a RetroArch version made by SuperrSonic specifically tuned for the Wii). It takes a bit of time to set it up correctly, but as a result it gives you lots of systems to emulate, lots of extra options and features (like removing slowdown on NES games using the fceumm core), what I perceive as the best picture quality and it's updated from time to time too.
